A DuckDuckGo search turned up several mentions of the recall in various business publications,
MacRumors,
EnGadget,
Apple Insider,
9 to 5 Mac,
Apple Insider,
Mashable,
Wired,
The Guardian, and so on, for several pages even including some local TV stations, so the news was out there. (Although I didn't find any reference in the Apple News app.)
But your point is well taken, but how were you supposed to be notified about the recall? Auto manufacturer's have the advantage that vehicle ownership and transfer records are maintained by the state and county governments in order to levy sales and property taxes. I don't think anyone would want that for our computing devices. Not everyone registers their computer with Apple and far fewer notify Apple or take any action to remove said computer from their account when they sell or junk it. I suspect a substantial number of Apple owners do not have an Apple ID and a significant portion of those that do, don't know what it is or why they have it.
Apple did make a press release, but in reality it was primarily reported only in the business and technology press — and one station in Cupertino. Widely read general circulation news magazines such as Time and Life are essentially a thing of the past and an announcement like that is unlikely to make the either the national or local television news. It is the kind item that might make the Late, Late, Late, news on the local PBS station. It would be picked up in the business or technology section of the New York Times, The Washington Post, or the Los Angeles Times but as influential as those newspapers are their readership is primarily local and only a few read from cover to cover.
Apple could have sent an email to everyone with an Apple ID, but unless Apple is in every Apple owner's
contact list a huge percentage of those would end up in the Spam folder, trash folder, or simply ignored. (I need to add Apple to my contacts.) Given there are several million more iPhone users than Mac users, any blanket emailing to Apple Account holders would very likely have created confusion and distress among millions of techno-phobic iPhone and iPad users.
My personal solution for keeping up with this kind of information is a subscription to
OS X Daily's daily email — which is a very brief description of the day's topic(s) and a link to the full article(s). It takes only a second or two to scan the email and decide if it is pertinent to me or not and then I can either delete it or explore it further. (That is how I found out Catalina and iOS 13 public beta were out.) Another resource is
MacRumor's Notifications. They send a notification any time an article, even a sideline, is posted. This can be too much, for example I have had to notifications since 9:45 this morning. Let that go too long without pruning the list and it can get to be unmanageable.